Heat vegetable oil in a fryer to 140°C.
Slice the potatoes into 1.5cm thick chips.
Fry the chips for 5-6 minutes until tender but not colored.
Remove the chips and increase the oil temperature to 190°C.
Fry the chips again for 3-4 minutes until golden.
Drain the chips on paper and season with salt.
Halve the lobster and remove meat from the claws, tail, and head.
Dice the lobster meat and return it to the shell.
Melt butter in a saucepan and fry shallots until soft.
Add stock, wine, and cream, then reduce by half via boiling.
Stir in mustard, herbs, and lemon juice then season.
Pre-heat the grill to its highest setting.
Spoon the sauce over the lobster and top with parmesan.
Grill the lobster for 3-4 minutes until golden brown.
Serve the lobster halves immediately alongside the chips.